Where can I download the Google Play Services SDK 7.8 even if it is a beta? I need it for the new Google Proximity Beacon API.
I can not get it with Eclipse or Android Studio.
It seems, that some have it allready.
The APK already started rolling out, just checked and my Nexus 5 and it's already on 7.8.
The APK is just one part though, and if you want to develop apps with Google Services, you also need the client library:
https://developers.google.com/android/guides/overview
The client library (which is what you add to your app to access the Play Services APIs, and which will later talk to the APK on the phone) is something you download via the Android SDK Manager. The latest available revision is still 25 though, which corresponds to Play Services 7.5.
TL;DR, we're still waiting for Play Services 7.8 with the Nearby API to be released in full.